1. Field of the Invention
This invention relates to a process for recovering hydrocarbons from a subterranean hydrocarbon-bearing formation. More particularly, this invention relates to a method of recovering hydrocarbons in which in the first step the formation is heated by injection of steam via an injection well and in a second step a mixture of carbon monoxide and hydrogen is pressured into the formation via the injection well and hydrocarbons are recovered from the formation via a production well.
2. Prior Art and Background
In recovery of petroleum from subterranean reservoirs, it usually is possible to recover only a minor portion of the petroleum in place by the so-called primary recovery techniques, that is, those techniques which utilize only the natural forces present in the reservoir. Thus, a variety of supplemental recovery techniques have been developed in order to increase the recovery of petroleum in such reservoirs. In these supplemental techniques which are commonly referred to as secondary recovery operations, although they may be tertiary in sequence of employment, energy is supplied to the reservoir as a means of moving the fluid within the reservoir to suitable production wells through which they may be withdrawn to the surface of the earth.
One of the newer developments in secondary recovery methods for petroleum and especially heavy crudes is the use of steam injection which has been applied in several modifications, including the "push-pull" technique and throughput methods and has resulted in significant recoveries in some areas of heavy crude reservoirs. Crude recovery by this process is enhanced through the beneficial effects of the drastic viscosity reduction characteristic of heavy crudes. This reduction in viscosity facilitates the production of hydrocarbons since it improves their mobility, i.e., increases they ability to flow.